1. Field of the Invention
The present invention concerns a fuel injection device for ramjets for supersonic and/or hypersonic aircraft, designed to operate over a wide range of speeds. The range of speeds envisaged is typically between Mach 1-2 and 15-20 (a contribution to the thrust could be envisaged at Mach 0.8, for example).
2. Description of the Prior Art
Ramjets are engines useful for propulsion of aircraft traveling at a wide range of speeds with a low specific consumption. The fuel usually employed for applications at high speeds is hydrogen, which is generally injected in gas form. Hydrocarbons, with a lower calorific value but a higher density, can also be used in part of the flight envelope. However, the correct distribution of the fuel throughout the stream, optimal mixing, correct ignition and stable combustion require high-performance injection devices both in the case of subsonic combustion and in the case of supersonic combustion. The phenomena associated with these two modes of combustion being different, the associated injection geometries are often different. Moreover, to operate over a wide range of flight conditions a ramjet supporting both modes of combustion, subsonic and supersonic, must accommodate the transition between them. This generally necessitates a mechanical modification of the geometry of the body of the ramjet and of the injection device.
This can naturally give rise to the problems in manufacture and in service.
An aim of the present invention is to eliminate these drawbacks and the present invention concerns an injection device assuring an aerodynamic transition rather than a mechanical transition between subsonic combustion and supersonic combustion.